This application relates to a grid utilized in a detector for instruments such as ion mobility and differential mobility spectrometers.
Ion mobility spectrometers (IMS) are utilized to identify trace materials in a gas stream. As an example, IMS instruments are known which detect the presence of trace amounts of chemical warfare agents, toxic industrial chemicals, or improvised explosive devices.
One type of IMS is known as a time of flight spectrometer. In time of flight, air is first ionized and then a gating device allows a small fraction of the ions to be analyzed to move into a drift tube. An electric field is applied along the drift tube and chemical species are separated based on their relative mobility, which in turn is a function of the ion's molecular weight and size
Downstream of the drift tube, there is typically a collector to communicate the collected ionized particles to a detector.
In some instances, the ionized particles can have both positive and negative ions. It would be efficient to detect both species simultaneously. However, proposals to date have required large electric fields and, thus, have complicated other locations along the detector system.
It has been known to make micro machined fine electrode grids. However, this type grid has been utilized for gating devices in such sensing systems and not at the collector location.